Question

Which changes requires an oxidising agent?

• A. $2 S _{2} O _{3}^{2-} \rightleftharpoons S _{4} O _{6}^{2-}$
• B. $Zn ^{2+} \rightleftharpoons Zn$
• C. $ClO ^{-} \rightleftharpoons Cl ^{-}$
• D. $SO _{3} \rightleftharpoons SO _{4}^{2-}$

Answer 1

Answer: (A)

The reaction which involves oxidation, requires an oxidising agent.

$S _{2} O _{3}^{2-} \rightarrow S _{4} O _{6}^{2-}$

S is undergoing oxidation. Oxidation state of S changes form 2 to 2.5 and hence this reaction requires an oxidising agent.